Flameless gas catalytic heater

ABSTRACT

Flameless gas catalytic heaters for local heating in explosive environments and installations whose operating principle is predicated on the catalytic oxidation of combustible gases as they pass through a porous catalytically active bed positioned in a heater housing whose side walls are hollow along the perimeter of the active bed and covered inside with a material having a high heat reflection coefficient.

United States Patent [191 Chapurin Jan. 8, 1974 FLAMELESS GAS CATALYTIC HEATER [76] Inventor: Gennady Alexandrovich Chapurin,

ulitsa Kadischeva 3, kv. 49, Saratov, U.S.S.R.

22] Filed: Jan. 28, 1972 211 App]. No.: 221,682

[52] US. Cl. 431/329 [51] Int. Cl. F23d 13/14 [58] Field of Search 431/328, 329

[56] References Cited UNITED STATES PATENTS 1.259.029 3/1918 Lucke 43l/329 3.024.836 3/1962 Bello 431/329 3.073.379

1/1963 -Martin 431/329 FOREIGN PATENTS OR APPLICATICNS l,458,l67 l0/l966 France 431/328 Primary Examiner-Carroll B. Dority, Jr. Att0rney-Holman & Stern [57] ABSTRACT Flameless gas catalytic heaters for local heating in explosive environments and installations whose operating principle is predicated on the catalytic oxidation of combustible gases as they pass through a porous catalytically active bed positioned in a heater housing whose side walls are hollow along the perimeter of the active bed and covered inside with a material having a high heat reflection coefficient.

4 Claims, 1 Drawing Figure 1 FLAMELESS GAS CATALYTIC HEATER BACKGROUND OF THE INVENTION PRIOR ART Such heaters are well-known.

In such heaters, the catalytically active layer attributing to oxidation of the flow ofa combustible gas passed therethrough to carbonic-acid gas and water and, therefore, providing for a flameless combustion" and heating of some object serves as the working body.

The catalytically active layer is confined within a cylindrical or rectangular body in such a manner that its one surface is essentially open and serves as a working surface radiating heat; in order to decrease sharply the heat losses of the surface through which the hot gas is delivered inside the catalytically active layer, this surface is thermally insulated by means of a layer made from a gas-proof material.

It is possible to cite as examples of such heaters the flameless gas catalytic heaters manufactured by the firms: Goigas, Sogena and Cis-Can Chemical industrial Sales," Ltd.; as well as those according to Austrian Pat. No. 234,954; Class 3612 2, and US. Pat. No. 3,073,379; Class 158-1 16.

A common disadvantage of conventional flameless gas catalytic heaters lies in non-uniform distribution of the temperature field along the surface of the catalytically active layer. As it is known, the central portion of the radiating surfaces is the hottest, and the portions adjoining the side walls of the body are the coldest. This is explained by great heat losses occurring through the side walls of the heater body. This disadvantage results in an incomplete (SO-90 percent) oxidation of the combustible gas and an appearance of carbonic-acid gas in combustion products.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the aforementioned disadvantages of conventional heaters.

The present invention has as its purposethe provision of a sufficiently effective insulation of mainly side walls oi the body.

This purpose is accomplished in that in aflameles's gas catalytic heater, according to the present invention, the walls of thebody lodging catalytically active heatinsulating layers are made hollow, and their internal surfaces confining a space inside the walls are made from a material having a high coefficient of reflection of thermal rays.

In order to decrease still greater the heat losses, it is expedient to provide vacuum a in the space of the walls of the body.

For the same purpose of decreasing the heat losses, the space in the walls of the body may be filledwith some inert gas.

This design of the walls of the body makes it possible to raise the degree of the combustible gas oxidation up to 100 percent.

The following detailed description of an exemplary embodiment of the present invention is given with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS The following detailed description of an exemplary embodiment of the present invention is given with reference to the accompanying drawing in which the sole FIGURE is a cross-sectional view of the flameless gas catalytic heater, built in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION The heater comprises a body 1 which may be of any shape, such as rectangular, cylindrical, etc. The side walls of the body 1 are made hollow. Internal surfaces 2 forming a space 3 inside the side walls are coated with a material having a high coefficient of reflection of thermal rays. Any conventional material of the kind, for instance aluminium, burnished stainless steel, etc., may be used as this material.

In order to decrease the heat losses, the space 3 may be filled with some gas, preferably an inert gas, in which case the danger of explosion is eliminated. The greatest effect of decreasing the heat losses is ensured by a providing vacuum in the space 3. Disposed inside the body 1 is a working member which is essentially a layer 4 made from some fibrous material, such as asbestos, silica, basaltic fiber, etc., impregnated with a catalyst of deep oxidation of carbonic-acid gases. Palladium, platinum, oxides of chromium, cobalt, copper, manganese, etc. are used as the catalyst.

The body 1 is designed in such a manner that a surface 5 of the layer 4 is open and serves a heatradiating surface.

Disposed immediately under the layer 4 is a layer 6 made from a porous heat-insulating material, such as asbestos, silica or basaltic fiber, which is not impregnated with the catalyst. Mounted on the body 1 at the side of the disposition of the porous heat-insulating layer is a gas-distributing device, which is fashioned as a pipe battery 7 located in a chamber 8 of the body I. The walls of the pipe battery 7 are punched through.

The heat-insulating layer 6 rests on a carrying shield 9 made from steel or aluminium and provided with a plurality of through holes. Mounted in the upper part of the body 1 is a metallic large-cell grid 10 used to protect the surface 5 of the layer 4 against mechanical damage. The grid 10 is pressed against the body I with the aid of a cover 11 having a port or opening 12. The cover 11 is secured to the body I with bolts 13.

The heater is provided with a thermal electric element 14 used for preheating the layer 4. The free end portions of the thermal electric element 14 are led through the bottom at the body 1 into a special explosion-proot box 15, with the elimination of the explosion possibility being ensured by a hermetic sealing of the box 15. Electric current is supplied to the thermal electric element via a cable (not shown in the drawing) which is introduced into the box 15 through a rubber sealing (not shown in the drawing).

The above-described flameless gas catalytic heater operates as follows.

In order to start the heater, electric current ofa voltage of 12 V is supplied via the cable to the thermal electric element 14. With the electric current passing along the spiral of the thermal electric element, the latter is heated and, due to the direct contact with the layer 4, heats the layer 4 to a temperature of about 400C at which the reaction of oxidation of the combustible gas starts.

Then, gas is delivered along a gas-supply line into a pipe branch 16. A natural gas, such as propane, butane, refinery gas, city gas and coke gas, may be used as such gas. While flowing out of the holes of the pipe battery 7 of the gas-distributing device, the combustible gas is uniformly distributed in the chamber 8, and, having passed through the pores of the heat-insulating layer 6, is delivered uniformly into the catalytically active layer 4. The combustible gas starts reacting with the oxygen of the air in the pores of the catalytically active layer 4 which is preheated by the thermal electric element to a temperature of the beginning of the oxidation reaction.

As a result of the catalytic reaction of the complete oxidation of the combustible gas by the oxygen of the air, there is liberated a great amount of heat, the layers 4 and 6 are heated, and the reaction continues in spite of the fact that the thermal electric element is switched-off. The ambient air is delivered into the catalytically active layer 4 by way of diffusion.

The combustion products, i.e., carbonic-acid gas and water, formed as a result ofthe reaction of the catalytic oxidation of the combustible gas, as well as free nitrogen of the air, are discharged into the atmosphere under the action of the thrust of the combustible gas delivered into the heater.

The catalytically active layer 4 and, more particularly, its surface 5, heated by the heat liberated during the reaction, becomes a source of infrared radiation. A uniform temperature falling within the range of 200+400C and depending on the amount of the combustible gas supplied to be combusted is provided uniformly along the whole radiating surface 5.

Thus, the heat load of the heater is set by varying the amount of the combustible gas supplied to be combusted. The maximum amount of the radiant energy is radiated by the radiating surface of the layer 4 within the wave length range of 3.5-5.6 microns. Within the working range of the heat loads in the combustion products there takes place practically no chemical incomplete combustion of the combustible gas.

What we claim is:

l. A flameless gas catalytic heater comprising a body defined by wall means including side walls having a sealed internal space; a material having a high coefficient of reflection of thermal rays provided on the inside of the side walls forming the internal space; a catalytically active porous layer through which combustible gases are passed and which ensures catalytic oxidation of the combustible gas; said layer being positioned within the body with at least its perimeter in contact with said side walls means; said layer having an open surface along which the products of oxidation of said combustible gas which has passed through this layer are delivered into the ambient atmosphere from the body; said catalytically active layer having a second surface along which said combustible gas is supplied inside said layer; and a heat-insulating porous layer adjoining the second surface of said catalytically active layer; said combustible gas also being passed through said heat insulating layer.

2. The heater according to claim 1, in which a vacuum is provided in said internal space disposed in said wall means of said body.

3. The heater according to claim 1, in which said internal space provided in said wall means of said body is filled with an inert gas.

4. A flameless gas catalytic heater comprising a body having a sealed hollow side wall, a bottom shield having a plurality of holes therein, and a cover having an opening therein, the inside of the hollow side wall being provided with a material having a high coefficient of reflection of thermal rays, a catalytically active porous layer within the body through which combustible gases are passed and which ensures catalytic oxidation of the combustible gas, said layer having an open surface facing the opening in the cover along which the products of oxidation of the combustible gas which is passed through the layer are delivered into the ambient atmosphere through the opening in the cup, said catalytically active layer having a second surface along which the combustible gas is supplied inside the layer, a heat insulating porous layer between said second surface and said shield through which the combustible gas passes, a chamber adjacent the shield in communication with the heat insulating porous layer via the holes in the shield, an apertured pipe battery located within the chamber in communication with a source of combustible gas for introducing the combustible gas into ing the catalytically active porous layer. 

2. The heater according to claim 1, in which a vacuum is provided in said internal space disposed in said wall means of said body.
 3. The heater according to claim 1, in which said internal space provided in said wall means of said body is filled with an inert gas.
 4. A flameless gas catalytic heater comprising a body having a sealed hollow side wall, a bottom shield having a plurality of holes therein, and a cover having an opening therein, the inside of the hollow side wall being provided with a material having a high coefficient of reflection of thermal rays, a catalytically active porous layer within the body through which combustible gases are passed and which ensures catalytic oxidation of the combustible gas, said layer having an open surface facing the opening in the cover along which the products of oxidation of the combustible gas which is passed through the layer are delivered into the ambient atmosphere through the opening in the cup, said catalytically active layer having a second surface along which the combustible gas is supplied inside the layer, a heat insulating porous layer between said second surface and said shield through which the combustible gas passes, a chamber adjacent the shield in communication with the heat insulating porous layer via the holes in the shield, an apertured pipe battery located within the chamber in communication with a source of combustible gas for introducing the combustible gas into the heat insulAting layer via the holes in the shield and a thermal electric element within the body for preheating the catalytically active porous layer. 